Petit has been an outspoken supporter of the death penalty and was critical of the state Supreme Court’s decision to abolish it. But he said his personal tragedy was not the impetus for running

Dr. William Petit, the sole survivor of the home invasion in Cheshire, Connecticut, opened up during an exclusive interview with NBC's "Today" show about the decision to run for the state House of Representatives and about moving forward after the tragedy that took his family nine years ago.

Petit’s wife, Jennifer Hawke Petit, and their two daughters, Hayley and Michaela, were killed during a night of horrors in their home in July 2007. Dealing with the survivor’s guilt will be part of Petit’s life forever, he said when asked.

“It’s packaged up and compartmentalized a little bit,” he said. “It’s sort of like on the top shelf in the closet in a small box and occasionally it comes out and you open the box and have a terrible night or a couple of terrible hours, or a terrible weekend, or whatever the case might be.”

“And then you come to grips and talk to your wife, and you talk to your son, and you talk to your family and your friends and you wrap it up again and you put it back in the closet knowing it’s probably never going to be gone,” Petit said.

He said the time after the murders was difficult. He was made president of the Petit Family Foundation, which was set up to honor the memory of Jennifer, Hayley and Michaela, but getting out of bed was difficult.

“I would basically would be in bed the entire day, then get up, come to the meeting and then, you know, go back to bed,” he said.

He has been an outspoken supporter of the death penalty and was critical of the state Supreme Court’s decision to abolish it. But he said his personal tragedy was not the impetus for running.

“You know, some people still stop and say, ‘I know where you stand. You’re for the death penalty.’ And I say, ‘Well, you know, I’m not really running on the death penalty," he said. "So what’s important to people is the quality of life, the economy, their jobs, their children’s futures.”

During an interview with NBC Connecticut last month, the retired endocrinologist said he wants to see state spending reined in. He said he agrees with the layoffs issued by Gov. Dannel Malloy because benefits like health insurance and pensions have gotten out of control.

The seat Petit is running for is now held by Betty Boukus, a Democrat, who has been in office for more than 20 years.